1. Field of the Invention
This invention relates generally to the etching of various materials downstream from microwave generated O.sub.2 Plasma, and more particularly to a method of controlling the selectivity of the etching of the materials in a composite of two materials in this type etching. In even more particular aspects this invention is related to the controlling of the etch selectivity downstream from a microwave generated O.sub.2 plasma for a composite of a polyimide material and a photoresist material.
2. Description of the Prior Art
Etching or "ashing" of various photoresist materials using O.sub.2 microwave generated plasma is well known in the art. U.S. Pat. No. 4,738,748 discusses the technique of ashing or etching of photoresist material. U.S. Pat. No. 4,341,592 assigned to Texas Instruments, Inc. further teaches the use of O.sub.2 microwave plasma for etching photoresist material and this patent also discusses the effect of various temperatures on the etching rate of various positive and negative photoresist materials in an O.sub.2 microwave material generated plasma.
U.S. Pat. Nos. 4,576,692; 4,718,976; 4,718,974; 4,673,456; 4,512,868; and 4,462,863 also suggest various arrangements for generation of O.sub.2 microwave plasma for various type of etching.
However, in many cases it is important to assure the selectivity of etching of various materials particularly photoresist materials and polyimide materials which are often formed in a composite configuration for many different processes such as photolithographic processing of integrated circuits and other types of devices.